KRTAP4-3 Gene: Keratin Associated Protein 4-3
A comprehensive biomedical resource on KRTAP4-3, covering gene structure, expression, and disease associations.
Gene Information Card
| Symbol | KRTAP4-3 |
|---|---|
| Full Name | Keratin Associated Protein 4-3 |
| Gene Type | protein coding |
| Chromosomal Location | 17q21.2 |
| NCBI Gene ID | 83891 ncbi.nlm.nih.gov/gene/83891 |
| Ensembl ID | ENSG00000244313 |
| UniProt ID | Q9BYR8 |
| OMIM ID | 611289 |
| HGNC ID | 18938 |
| Aliases | KAP4.3, KRTAP4.3 |
Description
KRTAP4-3 (Keratin Associated Protein 4-3) is a protein-coding gene located on chromosome 17q21.2. It encodes a member of the high-sulfur keratin-associated protein family, which are structural components of hair and nails. These proteins cross-link with keratin intermediate filaments to provide strength and rigidity to hair shafts. KRTAP4-3 is specifically expressed in the hair cortex and is involved in hair fiber formation. Mutations or altered expression may affect hair structure and have been studied in hair disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Woolly hair | Potential altered keratin cross-linking due to KRTAP4-3 variants | Limited evidence; gene expression in hair follicles suggests involvement, but direct causal mutations not yet confirmed in ClinVar. |
| Hair shaft abnormalities | Disruption of keratin-associated protein structure may affect hair integrity | Inferred from functional role; no specific disease association listed in OMIM or ClinVar. |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skin | Not available | Not detected |
| Hair follicle | Not available | High (based on gene function and tissue-specific expression) |
| Esophagus | Not available | Low |
| Tongue | Not available | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HaCaT (keratinocyte) | Not available | Keratinocyte cell line; expression may be low or absent as KRTAP4-3 is hair-specific. |
| A431 (epidermoid carcinoma) | Not available | Epithelial cell line; likely low expression. |
| NHEK (normal human epidermal keratinocytes) | Not available | Keratinocytes; expression not expected as KRTAP4-3 is hair-specific. |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| rs147238912 | SNV (missense) | 0.1% (global) | Potential impact on protein structure; no known disease association. |
| rs148211042 | SNV (missense) | 0.05% | Unknown effect; not reported in ClinVar. |
Mutation functional classification
Loss of Function (LOF)
No loss-of-function mutations have been characterized for KRTAP4-3. Given its role in hair structure, complete loss might lead to hair fragility, but no clinical evidence is available.
Gain of Function (GOF)
No gain-of-function mutations reported. Alterations could potentially affect cross-linking, but no functional studies exist.
Dominant Negative (DN)
No dominant-negative effects documented. As a structural protein, dominant-negative mutations could disrupt hair keratin network, but no evidence found.
View complete mutation data：
Gene Ontology (GO)
| • structural constituent of skin epidermis | • keratin filament binding |
| • biological_process: hair cycle | • cellular_component: intermediate filament |
Pathways
• Keratinization
• Formation of the cornified envelope
• Hair follicle development
Protein Summary
The KRTAP4-3 protein is a high-sulfur keratin-associated protein (KAP) that is a component of hair and nail matrix. It contains a characteristic cysteine-rich domain that forms disulfide bonds with keratin intermediate filaments, contributing to the mechanical strength of hair. The protein is approximately 20 kDa and is localized to the hair cortex. Its expression is tightly regulated during hair follicle differentiation. KRTAP4-3 belongs to the KAP4 family, which is known for high variability and rapid evolution.
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